Defined contribution and defined benefit retirement plans - Schedule of Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income (Loss) (Details) - Pension plans defined benefit - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Pension Plans Postretirement And Other Employee Benefits [Line Items]
Net actuarial gains (losses)	$ 16.0	$ (25.5)	$ 134.1
Amortization of unrecognized net actuarial losses	3.7	3.8	14.7
Amortization of unrecognized prior service cost (credit)	0.1		0.1
Settlements	0.4	6.5	0.4
Total	$ 20.2	$ (15.2)	$ 149.3